(1) FIELD OF THE INVENTION
This invention relates to a process for producing a polymer of monoallylamine (CH.sub.2 .dbd.CH-CH.sub.2 NH.sub.2).
(2) DESCRIPTION OF THE PRIOR ART
As is well known, allyl compounds are difficult to be polymerized with usual radical initiators and they only give a polymer having a low degree of polymerization in a low yield.
This is explained as being due to the occurrence of the self-termination reaction between allylic hydrogen atoms and radicals, and this reaction is usually called "allylic degradative chain transfer".
This fact is a common knowledge of polymer chemists, and is mentioned in many papers and textbooks [cf. for example, C. E. Schildknecht, "Allyl Compounds and their Polymers", Wiley-Interscience, 1973, pp. 29-30; and R. C. Laible, Chem. Rev. 58, (5), 807-843 (1958)].
Such is unexceptionally applicable also to monoallylamine which is a kind of allyl compound. Thus, monoallylamine hardly polymerizes with radical or ionic initiators, and only a few examples of polymerization have been reported in which the polymerization takes place under the following special conditions.
(1) The process of obtaining a brown-colored resinous polymonoallylamine (hereinafter simply referred to as "polyallylamine") by the gas phase polymerization using tetrafluorohydrazine as a catalyst (U.S. Pat. No. 3,062,798);
(2) The process of obtaining a black-brown colored, resinous polyallylamine hydrochloride having a molecular weight of 950-1,000 by adding a small amount of water to monoallylamine hydrochloride to bring it into a state of aqueous melt at 80.degree.-85.degree. C. and then polymerizing it while adding hydrogen peroxide in small portions [V. V. Zycova et al., Tr. Inst. Khim. Nauk, Akad, Nauk Kaz. SSR 11, 89-94 (1964); Chem. Abst. 61, 14855 (1964)].
(3) The process wherein monoallylamine hydrochloride is dissolved into a mixed solvent of tertbutyl alcohol and chlorobenzene in the coexistence of diethyl phosphite and then subjected to polymerization at a reflux temperature of the solvent using azobisisobutyronitrile as an initiator (see German Laid-Open No. 2946550 and its Japanese counterpart, Japanese Laid-Open No. 82807/1981).
The above-mentioned processes (1), (2) and (3) are examples of polymerization of monoallylamine in which catalysts such as radical initiators are used. However, in the processes (1) and (2), the polymers obtained are viscous and resinous and no polymer having a high degree of polymerization is obtained.
The process (3) disclosed in the German Laid-Open Gazette relates to homo- and copolymerization of monoallylamine hydrochloride. In the German patent Specification, all working examples except one mentioned at page 36 thereof are those of copolymerizing monoallylamine hydrochloride with a polymerizable vinyl monomer such as acrylamide, acrylic acid, acrylic acid ester and acrylonitrile. In the only one example of homopolymerization of monoallylamine hydrochloride disclosed at page 36 thereof, polyallylamine hydrochloride was obtained at a yield of 85%. However the German Laid-Open Gazette does not mention the properties and the polymerization degree of the polymer obtained but only discribes that it is water-soluble over the whole pH range. The present inventors have repeated the homopolymerization of monoallylamine hydrochloride disclosed at page 36 of the German Laid-Open Gazette and observed that in opposition to said disclosure, only a hygroscopic low molecular weight product was obtained at a low yield of about 0.6%. In this connection, no working example of homopolymerization of monoallylamine hydrochloride is found in the Japanese Laid-Open No. 82807/1981 which is the Japanese counterpart of the German Laid-Open Gazette.
The following radiation polymerization processes have also been proposed as processes for polymerizing monoallylamine. The monoallylamine polymers obtained by these processes have a higher degree of polymerization than that of the polymers obtained by the processes using radical type catalysts.
(4) The process of polymerizing monoallylamine in a protic acid (sulfuric acid, phosphoric acid or hydrochloric acid) while irradiating it with gamma rays or while irradiating it with ultraviolet rays in the presence of hydrogen peroxide [V. A. Kabanov et al., Vysokomol. Soed., 18, No. 9, 1957-1962 (1976); 18, No. 10, 2233-2238 (1976)].
(5) The process of irradiating monoallylamine, allyl cyanide or allylmercaptan with a variety of radiations (gamma rays, electron beams, X rays, ultraviolet rays) in the presence of an inorganic acid or an inorganic acid salt of a metal belonging to Group I or II of the periodic table (L. S. Polak, V. A. Kabanov et al., USSR Pat. No. 296,423). Though this USSR Patent includes polymerization processes using radical type catalysts, examples of the patent involve no case of polymerizing monoallylamine with radical type catalyst, only referring to a process of polymerizing allyl cyanide with benzoyl peroxide in the presence of zinc chloride and a process of polymerizing allylmercaptan with hydrogen peroxide in the presence of calcium chloride.
On the other hand, since polyallylamine is a practically quite interesting polymer, there have been made attempts to produce polyallylamine or its N-alkyl-substituted derivatives by the chemical modification of other vinyl polymers. As examples of such attempts, the followings can be referred to:
(6) The process of producing polyallylamine by hydrogenating polyacrylonitrile latex (U.S. Pat. No. 2,456,428);
(7) The process of synthesizing polyallylamine by the reduction of polyacrolein-oxime [Yoshikazu Hatsuhama et al., Kogyo Kagaku Zasshi 64, No. 3,595 (1961)];
(8) The process of obtaining a polymer of allyltrimethylammonium chloride by reacting an allyl chloride polymer having a molecular weight of about 900 with trimethylamine (U.S. Pat. No. 4,053,512); and
(9) The process of producing poly-(N,N-dimethylallylamine) by reducing a polymer of N,N-dimethylacrylamide (the same patent as above).
Among the nine processes for producing monoallylamine polymer or its N-alkyl-substituted derivatives mentioned above, the radiation polymerization processes with gamma rays in protic solvents mentioned in (4) and (5) are relatively preferable. As is well known, however, radiation polymerization process is not suitable as a process for producing a large maount of polymer, and at the present stage there is no case of industrially producing a polymer by radiation polymerization process. Thus, polyallylamine is not produced industrially even today, whereas monoallylamine has been industrially produced from many years ago.
An object of this invention is to provide a process for producing a polymer of monoallylamine, having a high degree of polymerization, by using a radical initiator.
Other and further objects, features and advantages of this invention will appear more fully from the following description.